Korn Shell [[ ... ]] operator

[Arindam]

I know csh is the shell of choice on FreeBSD. But I have this question
on Korn Shell and it would be great if somebody could explain.

Can someone tell me a little more about the Korn Shell [[ ... ]]
double-brackets construct used for comparing string expressions. How
does it differe from the standard [ ... ] single brackets.

You could tell me to RTFM but I haven't gleaned enough clarity from
such efforts already expended.

It would be great if you could give some idea through examples.

Cheers,
Andy
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